Nonlinear Processes in Geophysics最新文献

{"title":"Part 1: Multifractal analysis of wind turbine power and the associated biases","authors":"Jerry Jose, Auguste Gires, Yelva Roustan, Ernani Schnorenberger, Ioulia Tchiguirinskaia, Daniel Schertzer","doi":"10.5194/npg-2024-5","DOIUrl":"https://doi.org/10.5194/npg-2024-5","url":null,"abstract":"<strong>Abstract.</strong> The inherent variability in atmospheric fields, which extends over a wide range of temporal and spatial scales, also gets transferred to energy fields extracted off them. In the specific case of wind power generation, this can be seen in the theoretical power available for extraction in the atmosphere as well as the empirical power produced by turbines. Further the power produced by turbines are affected by atmospheric turbulence as well as other fields it interact with. For modelling as well as analyzing them, quantification of their variability, intermittency and correlations with other interacting fields is important. To understand the uncertainties involved in power production, power outputs from four 2MW turbines are analyzed from an operational wind farm at Pay d’Othe, 110 km southeast of Paris, France. Using simultaneously measured wind velocity from the same location, the variability in power available at the wind farm, and power produced by wind turbines were analyzed. To account for the intermittency and variability in said fields, the framework of Universal Multifractals (UM) is used. UM is a widely used, physically based, scale invariant framework for characterizing and simulating geophysical fields over a wide range of scales. While statistically analysing the power produced by the turbine, rated power acts like an upper threshold resulting in biased estimators. This is identified and quantified here using the theoretical framework of UM along with the actual sampling resolution of instruments under study. The validity of this bias in framework is further tested and illustrated using numerical simulations of fields with the same multifractal properties. Understanding instrumental thresholds and their effect in analysis is important in retrieving actual fields and modelling them, more so, in the case of power production where the uncertainties due to turbulence are already a leading challenge. This is further expanded in the second part where the influence of rainfall in power production is studied using scale invariant tools of UM and joint multifractals.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"6 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139667165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Leading the Lorenz-63 system toward the prescribed regime by model predictive control coupled with data assimilation","authors":"Fumitoshi Kawasaki, Shunji Kotsuki","doi":"10.5194/npg-2024-4","DOIUrl":"https://doi.org/10.5194/npg-2024-4","url":null,"abstract":"<strong>Abstract.</strong> In recent years, concerns have been raised regarding the intensification and increase of extreme weather events such as torrential rainfall and typhoons. To mitigate the damage caused by weather-induced disasters, recent studies have started developing weather control technologies to lead the weather to a desirable direction with feasible manipulations. This study proposes introducing the model predictive control (MPC), an advanced control method explored in control engineering, into the framework of the control simulation experiment (CSE). In contrast to previous CSE studies, the proposed method explicitly considers physical constraints such as the maximum allowable manipulations within the cost function of the MPC. As the first step toward applying the MPC to real weather control, this study performed a series of MPC experiments with the Lorenz-63 model. Our results showed that the Lorenz-63 system can be led to the positive regime with control inputs determined by the MPC. Furthermore, the MPC significantly reduced necessary forecast length compared to earlier CSE studies. It was beneficial to select a member showing a larger regime shift for the initial state when dealing with uncertainty in initial states.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139667534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new approach to understanding fluid mixing in process-study models of stratified fluids","authors":"Samuel George Hartharn-Evans, Marek Stastna, Magda Carr","doi":"10.5194/npg-31-61-2024","DOIUrl":"https://doi.org/10.5194/npg-31-61-2024","url":null,"abstract":"Abstract. While well-established energy-based methods of quantifying diapycnal mixing in process-study numerical models are often used to provide information about when mixing occurs, and how much mixing has occurred, describing how and where this mixing has taken place remains a challenge. Moreover, methods based on sorting the density field struggle when the model is under-resolved and when there is uncertainty as to the definition of the reference density when bathymetry is present. Here, an alternative method of understanding mixing is proposed. Paired histograms of user-selected variables (which we abbreviate USPs (user-controlled scatter plots)) are employed to identify mixing fluid and are then used to display regions of fluid in physical space that are undergoing mixing. This paper presents two case studies showcasing this method: shoaling internal solitary waves and a shear instability in cold water influenced by the nonlinearity of the equation of state. For the first case, the USP method identifies differences in the mixing processes associated with different internal solitary wave breaking types, including differences in the horizontal extent and advection of mixed fluid. For the second case, the method is used to identify how density and passive tracers are mixed within the core of the asymmetric cold-water Kelvin–Helmholtz instability.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"10 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139589636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multifractal structure and Gutenberg-Richter parameter associated with volcanic emissions of high energy in Colima, México (years 2013–2015)","authors":"Marisol Monterrubio-Velasco, Xavier Lana, Raúl Arámbula-Mendoza","doi":"10.5194/npg-2024-2","DOIUrl":"https://doi.org/10.5194/npg-2024-2","url":null,"abstract":"<strong>Abstract.</strong> The evolution of multifractal structures in physical processes, for instance, climatology, seismology or volcanology, contributes to detecting changes in the corresponding phenomena. The evolution of the multifractal structure of volcanic emissions of low, moderate, and high energy (Colima, México years 2013–2015) contributes to this research to detect quite evident signs of the immediacy of possible dangerous emissions of high energy close to 8.0x10⁸ J. These signs are manifested by the evolution of six multifractal parameters: the central Hölder exponent (α₀), the maximum and minimum Hölder exponents (α_max, α_min) the multifractal amplitude (<em>W</em>= α_max-α_min), the multifractal asymmetry (γ = [α_max-α₀]/[α₀-α_min]) and the complexity index, CI, which is defined as the addition of normalised values of α₀, <em>W</em> and γ. The results of the adapted Gutenberg-Richter seismic law to volcanic emissions of energy, as well as the corresponding skewness and standard deviation of the volcanic emission data, also contribute to confirming the results obtained using multifractal analysis. The obtained results, based on multifractal structure, adaptation of Gutenberg-Richter law to volcanic emissions, and basic statistical parameters, could be assumed as relevant to prevent a forthcoming volcanic episode of high energy, which could be additionally quantified by an appropriate forecasting algorithm.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"4 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139553450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Comparison of Two Nonlinear Data Assimilation Methods","authors":"Vivian A. Montiforte, Hans E. Ngodock, Innocent Souopgui","doi":"10.5194/npg-2024-3","DOIUrl":"https://doi.org/10.5194/npg-2024-3","url":null,"abstract":"<strong>Abstract.</strong> Advanced numerical data assimilation (DA) methods, such as the four-dimensional variational (4DVAR) method, are elaborate and computationally expensive. Simpler methods exist that take time-variability into account, providing the potential of accurate results with a reduced computational cost. Recently, two of these DA methods were proposed for a nonlinear ocean model. The first method is Diffusive Back and Forth Nudging (D-BFN) which has previously been implemented in several complex models, most specifically, an ocean model. The second is the Concave-Convex Nonlinearity (CCN) method provided by Larios and Pei that has a straightforward implementation and promising results. D-BFN is less costly than a traditional variational DA system but it requires integrating the model forward and backward in time over a number of iterations, whereas CCN only requires integration of the forward model once. This paper will investigate if Larios and Pei's CCN algorithm can provide competitive results with the already tested D-BFN within simple chaotic models. Results show that observation density and/or frequency, as well as the length of the assimilation window, significantly impact the results for CCN, whereas D-BFN is fairly adaptive to sparser observations, predominately in time.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"334 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139590099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sensitivity of the polar boundary layer to transient phenomena","authors":"Amandine Kaiser, Nikki Vercauteren, Sebastian Krumscheid","doi":"10.5194/npg-31-45-2024","DOIUrl":"https://doi.org/10.5194/npg-31-45-2024","url":null,"abstract":"Abstract. Numerical weather prediction and climate models encounter challenges in accurately representing flow regimes in the stably stratified atmospheric boundary layer and the transitions between them, leading to an inadequate depiction of regime occupation statistics. As a consequence, existing models exhibit significant biases in near-surface temperatures at high latitudes. To explore inherent uncertainties in modeling regime transitions, the response of the near-surface temperature inversion to transient small-scale phenomena is analyzed based on a stochastic modeling approach. A sensitivity analysis is conducted by augmenting a conceptual model for near-surface temperature inversions with randomizations that account for different types of model uncertainty. The stochastic conceptual model serves as a tool to systematically investigate which types of unsteady flow features may trigger abrupt transitions in the mean boundary layer state. The findings show that the incorporation of enhanced mixing, a common practice in numerical weather prediction models, blurs the two regime characteristic of the stably stratified atmospheric boundary layer. Simulating intermittent turbulence is shown to provide a potential workaround for this issue. Including key uncertainty in models could lead to a better statistical representation of the regimes in long-term climate simulation. This would help to improve our understanding and the forecasting of climate change in high-latitude regions.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"64 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139495235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aggregation of slightly buoyant microplastics in 3D vortex flows","authors":"Irina I. Rypina, Lawrence J. Pratt, Michael Dotzel","doi":"10.5194/npg-31-25-2024","DOIUrl":"https://doi.org/10.5194/npg-31-25-2024","url":null,"abstract":"Abstract. Although the movement and aggregation of microplastics at the ocean surface have been well studied, less is known about the subsurface. Within the Maxey–Riley framework governing the movement of small, rigid spheres with high drag in fluid, the aggregation of buoyant particles is encouraged in vorticity-dominated regions. We explore this process in an idealized model that is qualitatively reminiscent of a 3D eddy with an azimuthal and overturning circulation. In the axially symmetric state, buoyant spherical particles that do not accumulate at the top boundary are attracted to a loop consisting of periodic orbits. Such a loop exists when drag on the particle is sufficiently strong. For small, slightly buoyant particles, this loop is located close to the periodic fluid parcel trajectory. If the symmetric flow is perturbed by a symmetry-breaking disturbance, additional attractors for small, rigid, slightly buoyant particles may arise near periodic orbits of fluid parcels within the resonance zones created by the disturbance. Disturbances with periodic or quasiperiodic time dependence may produce even more attractors, with a shape and location that recurs periodically. However, not all such loops attract, and rigid particles released in the vicinity of one loop may instead be attracted to a nearby attractor. Examples are presented along with mappings of the respective basins of attraction.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"14 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139483819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of Advection-Diffusion Equation for Nonlinearly Evolving Precipitation Field","authors":"Ji-Hoon Ha","doi":"10.5194/npg-2023-28","DOIUrl":"https://doi.org/10.5194/npg-2023-28","url":null,"abstract":"<strong>Abstract.</strong> Analytic solutions for the Advection-Diffusion equation have been explored in diverse scientific and engineering domains, aiming to understand transport phenomena, including heat and mass diffusion, along with the movement of water resources. Precipitation, a vital component of water resources, presents a modeling challenge due to the complex interplay between advection-diffusion effects and source terms. This study aims to improve the modeling of nonlinearly evolving precipitation fields by specifically addressing advection-diffusion equations with time-varying source terms. Utilizing analytic solutions derived through the integral transform technique, we modeled the time-varying source term and investigated the correlation between advection-diffusion and source term effects. While the growth of the field is mainly influenced by the amplitude, size, and timescale of the source term, it can be modulated by advection and diffusion effects. When the timescale of source injection is significantly shorter than the dynamic scale of the system, advection and diffusion effects become independent of the field growth. Conversely, when the timescale of source term injection is sufficiently long, the system evolution primarily depends on advection and diffusion effects. In turbulent regimes with strong diffusion and weak advection effects, a quasi-equilibrium state between growth and decay can be established by regulating the decay caused by advection. However, in regimes where advection effects are crucial, the decay process predominates over the growth process.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"20 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139470798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On dissipation time scales of the basic second-order moments: the effect on the Energy and Flux-Budget (EFB) turbulence closure for stably stratified turbulence","authors":"Evgeny Kadantsev, Evgeny Mortikov, Andrey Glazunov, Nathan Kleeorin, Igor Rogachevskii","doi":"10.5194/egusphere-2023-3164","DOIUrl":"https://doi.org/10.5194/egusphere-2023-3164","url":null,"abstract":"<strong>Abstract.</strong> The dissipation rates of the basic turbulent second-order moments are the key parameters controlling turbulence energetics and spectra, turbulent fluxes of momentum and heat, and playing a vital role in turbulence modelling. In this paper, we use the results of Direct Numerical Simulations (DNS) to evaluate dissipation rates of the basic turbulent second-order moments and revise the energy and flux-budget turbulence closure model for stably stratified turbulence. We delve into the theoretical implications of this approach and substantiate our closure hypotheses through DNS data. We also show why the concept of down-gradient turbulent transport becomes incomplete when applied to the vertical turbulent flux of potential temperature under very stable stratification. We reveal essential feedback between turbulent kinetic energy, the vertical flux of buoyancy and turbulent potential energy, which is responsible for maintaining shear-produced stably stratified turbulence up to extreme static stability.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139470769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-frequency Internal Waves, High-mode Nonlinear Waves and K-H Billows on the South China Sea's Shelf Revealed by Marine Seismic Observation","authors":"Linghan Meng, Haibin Song, Yongxian Guan, Shun Yang, Kun Zhang, Mengli Liu","doi":"10.5194/egusphere-2024-92","DOIUrl":"https://doi.org/10.5194/egusphere-2024-92","url":null,"abstract":"<strong>Abstract.</strong> From July to September 2009, a set of multi-channel seismic data was collected in the northern shelf area of the South China Sea. After the data was processed, we observed a series of shoaling events on one of the survey lines, including high-frequency internal waves, high-mode nonlinear internal waves, and shear instability. Using theoretical results from previous numerical simulations and field observations, coupled with local temperature and salinity data, we analyzed their depth distribution, waveform characteristics, and formation mechanisms, and discussed the influence of seafloor topography and stratification on the shoaling of solitary internal waves. We estimated the mixing parameters of seawater using a parameterization scheme based on hydrographic data and seismic data, respectively. And we found that the diapycnal mixing caused by these shoaling events in the shelf area were about 3.5 times greater than those on the slope. Consequently, the fission of internal solitary waves and the induced shear instability serve as significant mechanisms for the energy dissipation of internal solitary waves at the slope and shelf of the South China Sea. Additionally, the high-frequency internal waves generated during shoaling might also have a crucial role in this process.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"54 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139461340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}